title: looking inside a working SiLED.
abstract: In this study, we investigate for the first time morphological and compositional changes of silicon quantum dot (SiQD) light-emitting diodes (SiLEDs) upon device operation. By means of advanced transmission electron microscopy (TEM) analysis including energy filtered TEM (EFTEM) and energy dispersive X-ray (EDX) spectroscopy, we observe drastic morphological changes and degradation for SiLEDs operated under high applied voltage ultimately leading to device failure. However, SiLEDs built from size-separated SiQDs operating under normal conditions show no morphological and compositional changes and the biexponential loss in electroluminescence seems to be correlated to chemical and physical degradation of the SiQDs. By contrast, we found that, for SiLEDs fabricated from polydisperse SiQDs, device degradation is more pronounced with three main modes of failure contributing to the reduced overall lifetime compared to those prepared from size-separated SiQDs. With this newfound knowledge, it is possible to devise ways to increase the lifetimes of SiLEDs.
authors.affiliation: Light Technology Institute (LTI) and DFG Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. florian.maier-flaig@kit.edu
authors.forename: Florian
authors.initials: F
authors.lastname: Maier-Flaig
authors.forename: Christian
authors.initials: C
authors.lastname: Kübel
authors.forename: Julia
authors.initials: J
authors.lastname: Rinck
authors.forename: Tobias
authors.initials: T
authors.lastname: Bocksrocker
authors.forename: Torsten
authors.initials: T
authors.lastname: Scherer
authors.forename: Robby
authors.initials: R
authors.lastname: Prang
authors.forename: Annie K
authors.initials: AK
authors.lastname: Powell
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Ozin
authors.forename: U
authors.initials: U
authors.lastname: Lemmer